This invention relates to computer systems. More specifically, the invention is concerned with a high-availability computer system comprising two or more processors, one of which acts as a primary processor, and another of which acts as a secondary or backup processor. The intention behind such a system is that, if the primary processor fails, the secondary processor can take over the total identity of the failed processor, thus ensuring that there is no loss in availability of the system to the user. Typically, in such a system, each processor has its own private disk drive or drives, and the system also includes one or more shared disk drives which are shared between the processors.
The invention is particularly, although not exclusively, concerned with computer systems running under the UNIX operating system (UNIX is a trademark of Unix System Laboratories). Much of a UNIX system's identity is contained within the directory /etc, which is part of the root filesystem and is normally held on the processor's private system disk. This includes information about users and their passwords, the system's network address, details of which filesystems are currently mounted and available to the system, and the startup processes of specific applications. However, a problem with this is that, when the secondary processor takes over from a failed primary processor, it may not have the most up-to-date version of this information available on its private system disk. For example, if users have changed their passwords, the new password information will be available only on the system disk of the failed processor.
The object of the present invention is to provide a novel way of solving this problem.